What would be really funny would be to find out that the energy levels at the LHC are not even close, that noting new happens, but there is no definitive disproof of anything. We shall know soon enough.
I would say that if he turns out to be right, or, as you say, it is stage on the way to something else, then Witten will go down in history has an equal of folks like Einstein and Newton. On the other hand, if he is totally wrong he will go down as one of the biggest smart-alexes (sp?) in history.
I worded my initial post pretty carefully. Note that I said nothing about his greatness as a physicist; I spoke only about his intelligence, which, by all accounts, is remarkable. It may well happen that he'll be remembered as much for his contributions to mathematics (which are substantial) as for his contributions to physics.
Good to hear from you again, BTW.